Nuchal Translucency

A nuchal translucency (NT) screening is typically included in the 11 to 14 week ultrasound.

This involves measuring the skin thickness at the back of the neck of a first trimester fetus.
Using a computer program that combines the NT thickness and the mother's age, we can estimate a baby's risk for certain chromosome problems, including trisomy 21, which causes Down Syndrome.

The first trimester screen test, which combines the NT measurement with a blood test, will estimate a baby's chance of having trisomy 21 based on the amounts of certain chemicals in the blood. The first trimester screen has the highest detection rate for Down Syndrome.
The only way to know for sure if Down Syndrome or another chromosome problem is present is to take a test such as chorionic villous sampling or amniocentesis. The disadvantage is that these tests may cause miscarriage.